diff --git a/src/main/java/org/mitre/synthea/world/concepts/PreferredProviders.java b/src/main/java/org/mitre/synthea/world/concepts/PreferredProviders.java
index af51a162ce..20d0db13e0 100644
--- a/src/main/java/org/mitre/synthea/world/concepts/PreferredProviders.java
+++ b/src/main/java/org/mitre/synthea/world/concepts/PreferredProviders.java
@@ -61,6 +61,11 @@ public Provider startNewRelationship(Person person, HealthRecord.EncounterType t
       provider = Provider.findService(person, HealthRecord.EncounterType.INPATIENT, speciality,
           time);
     }
+    if (provider == null) {
+      throw new IllegalStateException(
+          String.format("Unable to find provider for encounter type '%s' and specialty '%s'",
+              type, speciality));
+    }
 
     relationships.put(type, blankSafeSpecialty(speciality), provider);